The present invention is related to a supply line hose for use in a spray painting apparatus or installation. The spray painting apparatus provides for a dosed paint supply to the applicator or spray gun, and in particular for the case in which the applicator is charged at a high voltage for electrical atomizing of a electrically conductive paint or other fluid. Such a spray painting apparatus must be well insulated, explosion-resistant and reliable, without being excessively difficult or expensive to implement. When painting with direct charge of the fluid, using a conductive paint, the fluid in the hose will be charged with a voltage that may typically be up to 100 kV or so. For this reason, application with direct charge of conductive fluids such as water borne paints requires an effective insulation or galvanic blocking between a spray gun/applicator charged with a high voltage and apparatus at zero or ground potential, in particular a paint dosing device and/or the paint lines supplying the dosing device.
An international patent application WO IB2004/003104 (Anfindsen et al), assigned to ABB, which is hereby incorporated in full by means of this reference, describes an improved spray painting system with a dosing device. In particular it describes means for achieving a galvanic block, or voltage block, between the dosed fluid in contact with a high voltage and the fluid in the supply lines or paint kitchen etc which is normally at ground potential. In this description a dosing device is described which comprises one or more dosing cylinders which may be filled at a paint supply point, moved away from the supply point and towards a spray head connection point or docking head of a valve block for handling colour painting and flushing operations, and from there connected to one or more spray heads.
A supply line so connected between a dosing cylinder connection point or valve block and an applicator or spray head has to insulate the spray head the paint supply at high voltage in the supply line from the surroundings. It is known from, for example, U.S. Pat. No. 6,986,366 B2 entitled Piggable pipe for electrostatic coating of pieces, assigned to Duerr Systems GmbH, that known paint hoses constructed from multi-layer tubes to achieve sufficient insulating performance may have an unsatisfactory bending ability in use, i.e. insufficient ability to bend about the long axis of the hose, and are limited to bends with a large radius. It is known from an international application WO2007042990A1 entitled Paint application apparatus and system with same, assigned to ABB, to construct a flexible high voltage hose with an insulation gap containing air arranged between the inner hose and a second insulating layer.